We Keep Coding

Springboot Devtools not hot reloading?

I haven't used spring in a while, and I'm trying to get spring boot dev tools to perform hot reloading. I've imported the web and spring boot dependencies from start.spring.io project generator and made a uri for "/hello". I can run the project but changing the uri values doesn't hot reload and I don't believe that the hot reloading is working. From what I've found on searching the internet, the only necessary step is to add the hot reloading dependency in your pom file:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
My entire pom.xml file is as follows (generated from the start.spring.io website):
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.4.0</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.java</groupId>
<artifactId>java_app</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>java_app</name>
<description>Web Project</description>
<properties>
<java.version>11</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
And my web uri file is as follows (works, but without hot reloading):
package com.java.java_app;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
#SpringBootApplication
#RestController
public class JavaAppApplication {
public static void main(String[] args) {
SpringApplication.run(JavaAppApplication.class, args);
}
#GetMapping("/hello")
public String hello(#RequestParam(value = "name", defaultValue = "World") String name){
return String.format("Hello %s!", name);
}
}
This is as simple an application as I think it is possible to build, so I'm confused on what extra necessary step is needed to make hot reloading work. It does not appear to be documented say here (https://www.baeldung.com/spring-boot-devtools) other than to add the dependency. If it matters I'm running ubuntu 20.04.
EDIT:
I am running the application in the terminal on port :8080 and using vim to modify the uri file while the application is running. Since java has a lot of plugins for various IDEs someone suggested that it is worth mentioning that.

If you are not using an IDE you can use ./mvnw compile and the project will recompile while the editor is running.

Jar file not working in target folder but working in project folder

When I run the project in STS, it's working fine. All the pages in the webapp folder are loading in the browser. But when I build the project and run the JAR file (folder: D:\SpringBoot Projects\DemoExample\target) and go to the page URL, I'm getting Whitelabel error.
In another project I used spring security- In that project the login page is loading fine, but all the JSP pages in the webapp folder are not loading just like the above example.
While trying to solve this problem, I moved the JAR file from target folder to project folder (D:\SpringBoot Projects\DemoExample) and again ran the JAR file, now the JSP pages are loading fine. The JSP pages are only loading in that folder, if I moved the file to another folder, the pages are not loading.
I want to make sure that I can run the JAR file from any folder.
POM File:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.3.3.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.project</groupId>
<artifactId>DemoExample</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>DemoExample</name>
<description>Project</description>
<properties>
<java.version>11</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.tomcat/tomcat-jasper -->
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>tomcat-jasper</artifactId>
<version>9.0.37</version>
</dependency>
</dependencies>
<build>
<outputDirectory>${basedir}/${target.dir}/classes</outputDirectory>
<testOutputDirectory>${basedir}/${target.dir}/test-classes</testOutputDirectory>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
Main Class:
package com.example.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
#SpringBootApplication
public class DemoExampleApplication {
public static void main(String[] args) {
SpringApplication.run(DemoExampleApplication.class, args);
}
}
Controller:
package com.example.demo;
import org.springframework.web.bind.annotation.RequestMapping;
#org.springframework.stereotype.Controller
public class Controller {
#RequestMapping("/")
public String home() {
return "home.jsp";
}
}
JSP File:
<%# page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
Hello
</body>
</html>
Project Structure
Running Jar file in target folder
Result after running Jar file in target folder
Running Jar in project folder
Result after running Jar file in project folder

"Circular view path would dispatch back to the current handler URL." when using Spring Boot and Thymeleaf

When using Spring Boot and Thymeleaf, when trying to accessing the /home URL I am getting the following:
ServletException: Circular view path [home]: would dispatch back to the current handler URL [/home] again. Check your ViewResolver setup! (Hint: This may be the result of an unspecified view, due to default view name generation.)
pom.xml:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.3.3.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.demo</groupId>
<artifactId>watchlist</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>watchlist</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
main/java/com.demo.WatchlistApplication.java:
package com.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
#SpringBootApplication
public class WatchlistApplication {
public static void main(String[] args) {
SpringApplication.run(WatchlistApplication.class, args);
}
}
main/java/com.demo.controller.HomeController.java:
package com.demo.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.servlet.ModelAndView;
#Controller
public class HomeController {
#GetMapping("/home")
public ModelAndView home() {
return new ModelAndView("home");
}
}
main/resources/templates/home.html:
<html xmlns:th="http://www.thymeleaf.org">
<head>
<meta name="viewport" content="width = device-width, initial-scale = 1, shrink-to-fit = no">
<title>Web app</title>
</head>
<body>
<p th:text="'Hello world'"></p>
</body>
</html>

Annotate you controller class "HomeController" with annotation #RestController instead #Controller.
Seems duplicate of Circular View path error Spring boot

For springboot 2.6.0, Try controller:
#Controller
public class HomeController {
#GetMapping("/home")
public String home() {
return "home"; // be same as the template file name (without suffix)
}
}
You should have resources/templates/home.html.
Make sure the spring-boot-starter-thymeleaf has been downloaded successfully.

Basic spring boot app not working, showing: Failed to refresh live data from process xxxx

I am beginner for spring boot. I initialized a new project and tried to run it but it does not work successfully. WHen I run this as spring boot application, it starts execution. In bottom compiler/status bar, it shows processing and retrying. it goes upto 10 times and throw the following error:
Failed to refresh live data from process xxxx
More detail here
TanmayTestApplication.java
package com.example.tanmay_test;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
#SpringBootApplication
public class TanmayTestApplication {
public static void main(String[] args) {
SpringApplication.run(TanmayTestApplication.class, args);
}
}
DemoControler.java
package com.example.cntr;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.RequestMapping;
#RestController
public class DemoControler {
#RequestMapping(path = "/index")
public String index() {
return "By Tanmay!";
}
}
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.2.4.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>tanmay_test</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>tanmay_test</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>

I had the same problem in STS, and tried different things to resolve it. The following dependency for spring actuator makes that problem disappear, but however the main point of spring actuator provides more features than this. To learn more, click https://docs.spring.io/spring-boot/docs/current/reference/html/production-ready-features.html
The dependency should be added to your pom.xml file
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

I have faced the same problem but managed to solve it.
The controller class has to be in the "child package" relative to the TestApplication class.
In your case, your TanmayTestApplication class is in the package com.example.tanmay_test. Therefore, your DemoControler class must be inside the package com.example.tanmay_test.xxx.
**Note that xxx can be anything but extends from package com.example.tanmay_test. For example, package com.example.tanmay_test.web.
Hope this helps!

Add this line in your file application.properties (src/main/resources):
spring.devtools.livereload.enabled=true

Live data is collected with the help of Spring Actuator.
You need to include the following dependency in your pom.xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
See https://github.com/spring-projects/sts4/wiki/Live-Application-Information#application-requirements-for-spring-boot-projects for reference.

I was also facing same issue after adding Spring Actuator dependency, it resolved.
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
after adding this in POM.xml, do maven build and run again.

It is simply saying that you didn't enable LiveReload.

This is non other then the Data Source error
To resolves this I disabled the auto-configuration of the DataSource. And, this will not affect auto-configuring any other beans.
#SpringBootApplication(exclude = {DataSourceAutoConfiguration.class })

I'm using VS Code and the thing that worked for me was adding a dev tool dependency.
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
Also, add spring.devtools.livereload.enabled=true in application.properties file so that server knows that it has to reload every time a change is made.
Thanks for this one.

JSP and Spring Boot

I trying to build a simple welcome page (in jsp) using Spring Boot.
Below is the project structure
Application
#SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
public SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(Application.class);
}
}
APIController
#Controller
public class APIController {
#RequestMapping("/")
public String home() {
System.out.println("testing");
return "welcome";
}
}
When I access http://localhost:8080/, I get below error
This application has no explicit mapping for /error, so you are seeing
this as a fallback.
Wed May 23 15:31:51 MYT 2018 There was an unexpected error (type=Not
Found, status=404). No message available
By curl
{"timestamp":1527061233703,"status":404,"error":"Not Found","message":"No message available","path":"/"}
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>spring-boot-web-jsp</artifactId>
<packaging>war</packaging>
<name>Spring Boot Web JSP Example</name>
<description>Spring Boot Web JSP Example</description>
<version>1.0</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.4.2.RELEASE</version>
</parent>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<!-- This is a web application -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.apache.tomcat.embed</groupId>
<artifactId>tomcat-embed-jasper</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
</dependency>
<!-- Optional, test for static content, bootstrap CSS-->
<dependency>
<groupId>org.webjars</groupId>
<artifactId>bootstrap</artifactId>
<version>3.3.7</version>
</dependency>
</dependencies>
<build>
<plugins>
<!-- Package as an executable jar/war -->
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>

You have to define the prefix and suffix for you jsp file in application.properties file like following:
spring.mvc.view.prefix: /WEB-INF/jsp/
spring.mvc.view.suffix: .jsp

In directory \src\main\resources\static, Create a simple index.html file
<html>
<head>Hello, Bich Van</head>
<body>
<h3>Today is a rainny day</h3>
</body>
</html>
Then try again at http://localhost:8080
If you don't like static HTML files, you can use JSP, but need a little complicate. You need declaring JSP View resolver in Spring MVC configuration.
Reference document: https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-developing-web-applications.html#boot-features-spring-mvc-welcome-page

Ensure that you have jasper and jstl in the list of dependencies:
<dependency>
<groupId>org.apache.tomcat.embed</groupId>
<artifactId>tomcat-embed-jasper</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
</dependency>
Here is a working starter project - https://github.com/spring-projects/spring-boot/tree/master/spring-boot-samples/spring-boot-sample-web-jsp

It's better to use thymeleaf in your spring boot project and add the following dependency
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
In directory \src\main\resources\template, Create a simple index.html file